T  E 


PC-NRLF 


American  Society  of  Municipal 
Improvements,  1915 

SPECIFICATIONS  FOR 

Cement  Concrete  Paving 

ADOPTED  OCTOBER  14,  1915 


These  specifications  will  be  modified  from  time  to  time 
to  keep  them  fully  up  to  date.     Suggestions  as  to 
modifications   or    additions   are    solicited   and 
should  be  sent  to  the  Secretary,  or  to  Wil- 
liam J.  Hardee,City  Engineer,  New  Or- 
leans, La.,  Chairman  of  the  Sub- 
Committee  on  Specifications 
for  Concrete  Paving, 
and — 


GEORGE     W.     TILLSON 

Boro  Hall,  Brooklyn,  New  York 
Chairman  of  General  Committee  on  Standard  Specifications 


COPYRIGHTED,  1916 

Any  municipality  which  is  represented  in  tlle^mt-mbfc'rship  of  the  Society  by  one  or  more 
city  officials,  will  be  given  free  permission  to  use  these  specifications  or  any 
part  ot  them  upon  application  to  the  Secretary 


PUBLISHED  BY  THE  SOCIETY 
CHARLES  CARROLL  BROWN,  Secretary 

702  WULSIN  BUILDING 
INDIANAPOLIS,   INDIANA 


SPECIFICATIONS  FOR  CONCRETE  STREET 
PAVEMENT. 

ONE-COURSE  PAVEMENT.* 
i.  Materials. 

1.  Cement. — The    cement   shall    meet    the    requirements    of    the 
Standard     Specifications     for     Portland     Cement,     adopted    by    the 
American  Society  for  Testing  Materials,  August  16,   1909,  with  all 
subsequent    amendments    and    additions    thereto    adopted    by    said 
Society. 

2.  Fine  Aggregate. — Fine  aggregate  shall  consist  of  natural  sand 
or  screenings  from  hard,  tough,  durable  crushed  rock  or  gravel,  con- 
sisting of   quartzite   grains   or   other   equally   hard   material   graded 
from  fine  to  coarse,  with  the  coarse  particles  predominating.     Fine 
aggregate,  when  dry,  shall  pass  a  screen  having  four  (4)  meshes  per 
linear  inch;  not  more  than  twenty-five   (25)    per  cent  shall,  pass  a 
sieve  having  fifty   (50)    meshes  per  linear  inch,  and  not  more  than 
five    (5)    per   cent   shall   pass    a   sieve   having   one   hundred    (100) 
meshes  per  linear  inch.     Fine  aggregate  shall  not  contain  vegetable 
or  other  deleterious   matter  nor  more   than   three    (3)    per  cent  of 
clay  or  loam. 

Fine  aggregate  shall  be  of  such  quality  that  mortar  composed  of 
one  (1)  part  Portland  cement  and  three  (3)  parts  fine  aggregate, 
by  weight,  when  made  into  briquettes,  shall  show  a  tensile  strength 
(at  seven  (7)  and  twenty-eight  (28)  days)  at  least  equal  to  the 
strength  of  briquettes  composed  of  one  (1)  part  of  the  same  cement 
and  three  (3)  parts  Standard  Ottawa  sand  by  weight.  The  per- 
centage of  water  used  in  making  the  briquettes  of  cement  and  fine 
aggregate  shall  be  such  as  to  produce  a  mortar  of  the  same  consistency 
as  that  of  the  Ottawa  sand  briquettes  of  Standard  consistency.  In 
other  respects  all  tests  shall  be  made  in  accordance  with  the  Report 
of  Committee  on  Uniform  Tests  of  Cement  of  the  American  Society 
of  Civil  Engineers. 

3.  Coarse  Aggregate. — Coarse  aggregate  shall  consist    of    clean, 
tough,  crushed  rock  or  gravel,  or  slag  of  approved  quality  in  graded 

*  Specifications  regarding  both  joints  and  reinforcement  are  purposely  omitted 
from  these  specifications,  in  order  that  the  freest  opportunity  may  be  afforded 
for  their  addition,  in  any  particular  case,  according  to  the  opinions  of  the 
engineers  in  charge  under  the  local  conditions. 


342933 


sizes,  free  from  vegetable  or  other  deleterious  matter  and  containing 
no  soft,  flat  or  elongated  particles. 

The  sizes  of  the  coarse  aggregate  shall  be  such  as  to  pass  a  one  and 
one-half  (Ij^z")  inch  round  opening,  and  shall  range  from  one  and 
one-half  (Ij^")  inch  down,  not  more  than  five  (5)  per  cent  passing 
a  one-quarter  (%")  mch  round  opening,  and  with  no  intermediate 
sizes  removed. 

Its  "Coefficient  of  wear"  as  determined  by  the  "Deval  Test" 
shall  not  be  less  than  twelve,  and  its  crushing  strength  shall  not  be 
less  than  twenty  thousand  (20,000)  pounds  per  square  inch.** 

2.  Proportions. 

4.  All  proportions  of  cement,  fine  aggregate  and  coarse  aggregate 
shall  be  determined  on  the  basis  of  volumetric  analysis,  with  a  view 
to  obtaining  a  uniform  density  for  the  resulting  concrete. 

5.  An  examination  of  the  coarse  aggregate  to  be  used  shall  be 
made   and   the   voids   therein   determined.      The   amount   of   mortar 
(fine  aggregate  and  cement  mixed  with  water)  to  be  used  shall  then 
exceed  these  voids  in  volume  by  not  less  than  five    (5)    nor  more 
than  ten   (10)   per  cent  of  the  total  mass  of  the  coarse  aggregate. 

6.  An   examination   of    the   fine   aggregate   to   be   used   shall   be 
made  and  the  voids  therein  determined.     The  amount  of  cement  to 
be  used  shall  then  exceed  these  voids  in  volume  by  not  less  than  five 
(5)   nor  more  than  ten   (10)   per  cent  of  the  total  mass  of  the  fine 
aggregate. 

(Added  by   General  Committee.) 

In  no  case  shall  the  volume  of  fine  aggregate  be  less  than  one- 
half  the  volume  of  the  coarse  aggregate,  nor  shall  the  proportion 
of  cement  to  fine  aggregate  be  leaner  than  one  (1)  to  two  (2).  A 
cubic  yard  of  concrete  in  place  shall  contain  not  less  than  seven  sacks 
of  cement. 

7.  The   amount   of   water    to    be    used    shall    be    determined    by 
trial  mixtures  with  the  coarse  aggregate,  fine  aggregate  and  cement 
in  the  proportions  as  above  determined  until  a  satisfactory  consistency 
is  obtained  in  the  wet  concrete,  which  consistency  shall  be  such  as 
to  permit  the  concrete  to  be  readily  deposited  in  place  and  yet  hold 

**Figures  should  be  suited  to  local  conditions. 

9 


its  shape  when  struck  off  by  the  template  and  at  the  same  time  not 
to  bring  about  a  segregation  of  the  different  sizes  of  material  in 
handling.  Every  effort  and  precaution  shall  be  used  to  secure  a 
constant  uniformity  in  the  consistency  of  the  mix. 

J.  Sub-Grade. 

8.  Construction. — The  bottom  of   the  excavation  or  the  top  of 
the  fill  when  completed  shall  be  known  as  the  sub-grade  and  shall 
be  at  all  places  true  to  the  elevation  as  shown  on  the  plans  attached 
hereto. 

The  sub-grade  shall  be  brought  to  a  firm,  unyielding  surface  by 
rolling  the  entire  area  with  a  self-propelled  roller  weighing  not  less 
than  five  (5)  nor  more  than  ten  (10)  tons,  and  all  portions  of  the 
surface  of  the  sub-grade  which  are  inaccessible  to  the  roller  shall 
be  thoroly  tamped  with  a  hand  tamp  weighing  not  less  than 
fifty  (50)  lb.,  the  face  of  which  shall  not  exceed  one  hundred  (100) 
sq.  in.  in  area.  All  soft,  spongy,  or  yielding  spots  and  all  vegetable 
or  other  perishable  matter  shall  be  entirely  removed  and  the  space 
refilled  with  suitable  material. 

When  considered  necessary  or  of  assistance  in  producing  a  com- 
pact, solid  surface,  the  sub-grade  before  being  rolled  shall  be  well 
sprinkled  with  water. 

When  the  concrete  pavement  is  to  be  constructed  over  an  old 
pavement  composed  of  gravel  or  macadam,  the  latter  shall  be  entirely 
loosened  and  the  material  spread  for  the  full  width  of  the  pavement 
and  rolled.  All  interstices  shall  be  filled  with  fine  material  and 
rolled  to  make  a  dense,  tight  surface. 

9.  Acceptance. — No   concrete   shall   be    deposited   until   the   sub 
grade  is  checked  and  accepted  by  the  engineer. 

4.  Forms. 

10.  Materials. — Where   forms   are   required,   they   shall   be   free 
from  warp,  of  sufficient  strength  to  resist  spring  out  of  shape.  Wooden 
forms  shall  be  of  not  less  than  two-inch  stock. 

1 1 .  Setting. — The  forms  shall  be  well  staked  or  otherwise  held 
to  the  established  line  and  grades.     Where  the  curb  is  to  be  con- 
structed  integrally  with  the  pavement,   the  upper  edge  of  the  side 
forms  shall  conform  to  the  top  of  the  curb. 


12.  Treatment — All  mortar  and  dirt  shall  be  removed  from  the* 
forms  that  have  previously  been  used. 

13.  Precautions  shall  be  taken  to  prevent  leaks  thru  side  forms 
that  would   allow  the  cement  or   mortar   to   be   carried  out  of  the 
coarser  aggregate  along  the  edges  of  the  roadway. 

5.   Measuring   Materials   and   Mixing    Concrete. 

14.  Measuring  Materials. — The  method  of  measuring  the  mater- 
ials for  the  concrete,  including  water,  shall  be  one  which  will  insure 
separate   and   uniform   proportions   of   each   of   the   materials   at   all 
times.     A  bag  of  Portland  cement   (94  Ib.  net)   shall  be  considered 
one  ( 1 )  cu.  ft. 

15.  Mixing. — The  materials  shall  be*  mixed  in  a  batch  mixer  of 
approved  type  and  mixing  shall  continue  after  all  materials  are  in 
the  drum  for  at  least  one  ( 1 )  minute  at  a  minimum  speed  of  twelve 
(12)  revolutions  per  minute.     The  drum  shall  be  completely  emptied 
before  receiving  materials  for  successive  batches. 

16.  Re-Tempering. — Re-Tempering  of  mortar  or  concrete  which 
has  partially  hardened,  that  is,  re-mixing  with  or  without  additional 
materials  or  water,  shall  not  be  permitted. 

6.   Placing  Concrete. 

17.  Placing    Concrete. — Immediately    prior    to    placing   the   con- 
crete, the  sub-grade  shall  be  brought  to  an  even  surface.     The  sur- 
face   of    the    sub-grade    shall    be    thoroly    wet,    but    shall    show    no 
pools  of  water  when  the  concrete  is  placed. 

After  mixing,  the  concrete  shall  be  deposited  rapidly  upon  the  sub- 
grade  to  the  required  depth  and  for  the  entire  width  of  the  pave- 
ment in  successive  batches  and  in  a  continuous  operation  without 
the  use  of  intermediate  forms  or  bulkheads  between  expansion  joints. 

In  case  of  a  breakdown,  concrete  shall  be  mixed  by  hand  to  com- 
plete the  section  or  an  intermediate  transverse  joint  placed  at  the 
point  of  stopping  work.  Any  concrete  in  excess  of  that  needed  to 
complete  a  section  at  the  stopping  of  work  shall  not  be  used  in  the 
work. 

18.  Finishing. — The  surface  of  the  concrete  shall  be  struck  off 
for  the  entire  width  of  the  pavement  and  from  back  to  back  of  in- 
tegral curbs  when  used,  by  means  of  a  template  or  strikeboard.     Any 


holes  left  by  removing  any  material  or  device  used  in  constructing 
the  joint  shall  be  immediately  filled  with  mortar  composed  of  one 
(1)  part  cement  and  two  (2)  parts  of  fine  aggregate.  Concrete 
adjoining  metal  protection  plates  of  transverse  joints  shall  be  dense 
in  character  and  shall  be  given  a  smooth  finish  with  a  steel  trowel 
for  a  distance  of  six  (6)  in.  on  each  side  of  the  joints. 

After  being  brought  to  the  established  grade  with  the  template  or 
strikeboard,  the  concrete  shall  be  finished  from  a  suitable  bridge, 
no  part  of  which  shall  come  in  contact  with  the  concrete.  If  ap- 
proved by  the  engineer,  the  contractor  may  use  a  mechanical  striking 
and  finishing  machine.  The  concrete  shall  be  finished  with  a  wood 
float  in  a  manner  to  thoroly  compact  it  and  produce  a  surface  free 
from  depressions  or  inequalities  of  any  kind. 

The  finished  surface  of  the  pavement  shall  not  vary  more  than 
one-quarter  (/4)  in.  from  the  true  shape. 

7.  Protection. 

19.  Curing  and  Protection. — Excepting  as  hereinafter  specified, 
the  surface  of  the  pavement  shall  be  sprayed,  with  water  as  soon  as 
the  concrete  is  sufficiently  hardened  to  prevent  pitting,  and  shall  be 
kept  wet  until  an  earth  or  other  approved  covering  is  placed.  As 
soon  as  it  can  be  done  without  damaging  the  concrete,  the  surface 
of  the  pavement  shall  be  covered  with  not  less  than  two  (2)  in.  of 
earth  or  other  material  approved  by  the  engineer,  which  cover  shall  be 
kept  wet  for  at  least  ten  (10)  days.  When  deemed  necessary  or 
advisable  by  the  engineer,  freshly  laid  concrete  shall  be  protected  by 
canvas  until  such  covering  can  be  placed. 

Under  the  most  favorable  conditions  for  hardening  in  hot  weather, 
the  pavement  shall  be  closed  to  traffic  for  at  least  fourteen  (14)  days 
and  in  cool  weather  for  an  additional  time,  to  be  determined  by  the 
engineer. 

At  the  season  of  the  year  when  the  average  temperature  is  below 
50  degrees  Fahrenheit,  sprinkling  and  covering  of  the  pavement  may 
be  omitted  at  the  direction  of  the  engineer. 

The  contractor  shall  erect  and  maintain  suitable  barriers  to  pro- 
tect the  concrete  from  traffic  and  any  part  of  the  pavement  damaged 
from  traffic  or  other  causes,  occuring  prior  to  its  official  acceptance, 
shall  be  repaired  or  replaced  by  the  contractor  at  his  expense,  in  a 


manner  satisfactory  to  the  engineer.  Before  the  pavement  is  thrown 
open  to  traffic  the  covering  shall  be  removed  and  disposed  of  as 
directed  by  the  engineer. 

20.  Temperature  Below  35  Degrees  Fahrenheit. — Concrete  shall 
not  be  mixed  or  deposited  when  the  temperature  is  below  frezing. 

If  at  any  time  during  the  progress  of  the  work  the  temperature  is, 
or  in  the  opinion  of  the  engineer  will,  within  twenty-four  (24)  hours 
drop  to  thirty-five  (35)  degrees  Fahrenheit,  the  water  and  aggregates 
shall  be  heated,  and  precautions  taken  to  protect  the  work  from 
freezing  for  at  least  ten  (10)  days.  In  no  case  shall  concrete  be 
deposited  upon  a  frozen  sub-grade. 


TWO-COURSE  PAVEMENT.* 
/.  Materials. 

1.  Cement. — The    cement    shall    meet    the    requirements    of    the 
Standard  Specifications  for  Portland  Cement,  adopted  by  the  Ameri- 
can Society  for  Testing  Materials,  August  16,  1909,  with  all  subse- 
quent amendments  and  additions  thereto  adopted  by  said   Society. 

2.  Fine  Aggregate. — Fine  aggregate  shall  consist  of  natural  sand 
or  screenings  from  hard,  tough,  durable  crushed  rock  or  gravel,  con- 
sisting of   quartzite   grains   or   other   equally   hard   material   graded 
from  fine  to  coarse,  with  the  coarse  particles  predominating.     Fine 
aggregate,  when  dry,  shall  pass  a  screen  having  four  (4)  meshes  per 
linear  inch;  not  more  than  twenty-five    (25)    per  cent  shall  pass  a 
sieve  having  fifty   (50)    meshes  per  linear  inch,  and  not  more  than 
five  (5)  per  cent  shall  pass  a  sieve  having  one  hundred  (100)  meshes 
per  linear  inch.     Fine  aggregate  shall  not  contain  vegetable  or  other 
deleterious  matter  nor  more  than  three  per  cent  of  clay  or  loam. 

Fine  aggregate  shall  be  of  such  quality  that  mortar  composed  of 
one  (1)  part  Portland  cement  and  three  (3)  parts  fine  aggregate, 
by  weight,  when  made  into  briquettes,  shall  show  a  tensile  strength 
(at  seven  (7)  and  twenty-eight  (28)  days)  at  least  equal  to  the 
strength  of  briquettes  composed  of  one  ( 1 )  part  of  the  same  cement 
and  three  (3)  parts  Standard  Ottawa  sand  by  weight.  The  per- 

*Specifications  regarding  both  joints  and  reinforcement  are  purposely  omitted 
from  these  specifications,  in  order  that  the  freest  opportunity  may  be  afforded 
for  their  addition,  in  any  particular  case,  according  to  the  opinions  of  the 
engineers  in  charge  under  the  local  conditions. 

6 


centage  of  water  used  in  making  the  briquettes  of  cement  and  fine 
aggregate  shall  be  such  as  to  produce  a  mortar  of  the  same  con- 
sistency as  that  of  the  Ottawa  sand  briquettes  of  Standard  con- 
sistency. In  other  respects  all  tests  shall  be  made  in  accordance  with 
the  Report  of  Committee  on  Uniform  Tests  of  Cement  of  the 
American  Society  of  Civil  Engineers. 

3.  Coarse   Aggregate. — Coarse   aggregate   shall   consist  of   clean, 
tough,  crushed  rock  or  gravel,  or  slag  of  approved  quality,  in  graded 
sizes,  free  from  vegetable  or  other  deleterious  matter  and  containing 
no  soft,  flat  or  elongated  particles. 

The  sizes  of  the  coarse  aggregate  shall  be  such  as  to  pass  one  and 
one-half  (1^")  inch  round  opening  and  shall  range  from  one  and 
one-half  (I1/*"}  inch  down,  not  more  than  five  (5)  per  cent  passing 
a  one-quarter  (^4")  inch  round  opening. 

Its  "coefficient  of  wear"  as  determined  by  the  "Deval  test"  shall 
not  be  less  than  twelve  »(12)  and  its  crushing  strength  shall  not 
be  less  than  twenty  thousand  (20,000)  pounds  per  sq.  in.** 

No.   1  Aggregate  for  Wearing  Course. 

No.  1  aggregate  for  the  wearing  course  shall  consist  of  that  por- 
tion of  the  above  described  coarse  aggregate,  which,  when  dry,  will 
pass  a  one-half  (J^")  inch  round  opening  and  contain  not  more  than 
ten  (10)  per  cent  of  the  fine  material  which  will  pass  a  one-quarter 
(J4")  mcn  round  opening. 

No.  2  Aggregate  for  Wearing  Course. 

No.  2  aggregate  for  the  wearing  course  shall  consist  of  that  por- 
tion of  the  above  described  course  aggregate,  which  will  pass  a  one 
( 1 )  inch  round  opening,  ranging  in  size  from  one  ( 1 )  inch  down 
and  containing  not  more  than  five  (5)  per  cent  of  fine  material  that 
will  pass  a  one-quarter  (^")  inch  round  opening,  and  with  no 
intermediate  sizes  removed. 

2.  Proportions. 

4.  All  proportions  of  cement,   fine  aggregate  and   coarse  aggre- 
gate shall  be  determined  on  the  basis  of  volumetric  analysis,  with  a 
view  to  obtaining  a  uniform  density  for  the  resulting  concrete. 

** Figures  should  be  suited  to  local  conditions. 

7 


5.  An  examination  of  the  coarse  aggregate  to  be  used  shall  be 
made   and   the   voids   therein   determined.      The   amount   of   mortar 
(fine   aggregate   and   cement   mixed   with   water)    to   be   used   shall 
then   exceed  these  voids  in  volume  by  not  less   than   five    (5)    nor 
more  than  ten  (10)  per  cent  of  the  total  mass  of  the  coarse  aggregate. 

6.  An  examination  of  the  fine  aggregate  to  be  used  shall  be  made 
and   the  voids   therein   determined.     The   amount   of   cement   to   be 
used  shall  then  exceed  these  voids  in  volume  by  not  less  than  five 
(5)   nor  more  than  ten   (10)   per  cent  of  the  total  mass  of  the  fine 
aggregate. 

7.  The  amount  of  water  to  be  used  shall  be  determined  by  trial 
mixtures   with   the  coarse   aggregate,   fine   aggregate   and   cement   in 
the  proportions  as  above  determined  until  a  satisfactory  consistency 
is  obtained  in  the  wet  concrete,  which  consistency  shall  be  such  as 
to  permit  the  concrete  to  be  readily  deposited  in  place  and  yet  hold 
its  shape  when  struck  off  by  the  template  and  at  the  same  time  not 
to  bring  about   a  segregation   of   the   different  sizes  of   material   in 
handling.      Every   effort   and   precaution   shall   be   used   to   secure   a 
constant  uniformity  in  the  consistency  of  the  mix. 

(Added  by   General  Committee.) 

In  the  base  the  volume  of  the  fine  aggregate  shall  not  be 
less  than  one-half  (^2)  the  volume  of  the  coarse  aggregate  nor 
shall  the  proportion  of  cement  to  fine  aggregate  be  leaner  than  one 
(1)  to  two  and  one-half  (2^).  A  cubic  yard  of  concrete  shall  con- 
tain not  less  than  five  and  one-half  (5j/£)  sacks  of  cement. 

In  the  wearing  surface  the  volume  of  fine  aggregate  shall  not  be 
less  than  one-half  (^2)  the  volume  of  mixture  No.  1,  nor  shall  the 
proportion  of  cement  to  fine  aggregate  be  leaner  than  one  ( 1 )  to 
one  ( 1 ) .  A  cubic  yard  of  concrete  for  wearing  course  in  place  shall 
contain  not  less  than  twelve  (12)  sacks  of  cement. 

In  the  wearing  surface  the  volume  of  fine  aggregate  shall  not  be 
less  than  one-half  (J4)  the  volume  of  mixture  No.  2,  nor  shall  the 
proportion  of  cement  to  fine  aggregate  be  leaner  than  one  ( 1 )  to 
one  and  one-half  (Ij^).  A  cubic  yard  of  concrete  for  wearing 
course  in  place  shall  contain  not  less  than  eight  and  one-half  sacks 
of  cement. 


J.  Sub-Grade. 

8.  Construction. — The  bottom  of  the  excavation  or  the  top  of 
the  fill  when  completed  shall  be  known  as  the  sub-grade  and  shall 
be  at  all  places  true  to  the  elevation  as  shown  on  the  plans  attached 
hereto. 

The  sub-grade  shall  be  brought  to  a  firm,  unyielding  surface  by 
rolling  the  entire  area  with  a  self-propelled  roller  weighing  not  less 
than  five  (5)  nor  more  than  ten  (10)  tons,  and  all  portions  of  the 
surface  of  the  sub-grade  which  are  inaccessible  to  the  roller  shall 
be  thoroly  tamped  with  a  hand  tamp  weighing  not  less  than  fifty 
(50)  lb.,  the  face  of  which  shall  not  exceed  one  hundred  (100) 
sq.  in.  in  area.  All  soft,  spongy  or  yielding  spots  and  all  vegetable 
or  other  perishable  matter  shall  be  entirely  removed  and  the  space 
refilled  with  suitable  material. 

When  considered  necessary  or  of  assistance  in  producing  a  compact, 
solid  surface,  the  sub-grade  before  being  rolled  shall  be  well  sprinkled 
with  water. 

When  the  concrete  pavement  is  to  be  constructed  over  an  old 
pavement  composed  of  gravel  or  macadam,  the  latter  shall  be  entirely 
loosened  and  the  material  spread  for  the  full  width  of  the  pavement 
and  rolled.  All  interstices  shall  be  filled  with  fine  material  and 
rolled  to  make  a  dense,  tight  surface  of  the  roadbed. 

9.  Acceptance. — No   concrete   shall   be    deposited   until   the   sub- 
grade  is  checked  and  accepted  by  the  engineer. 

4.  Forms. 

10.  Materials. — Where    forms,  are   required,    they  shall   be   free 
from  warp,  of  sufficient  strength  to  resist  springing  out  of  shape; 
wooden  forms  shall  not  be  less  than  two   (2)   in.  stock. 

11.  Setting. — The  forms  shall  be  well  staked  or  otherwise  held 
to  the  established  line  and  grades.     Where  the  curb  is  to  be  con- 
structed integrally  with  the  pavement,   the  upper  edge  of  the  side 
forms  shall  conform  to  the  top  of  the  curb. 

12.  Treatment. — All  mortar  and  dirt  shall  be  removed  from  the 
forms  that  have  previously  been  used. 

13.  Precautions  shall  be  taken  to  prevent  leaks  thru  side  forms 
that  would   allow   the   cement   or   mortar  to   be   carried   out  of   the 
coarser  aggregate  along  the  edges  of  the  roadway. 

9 


5-  Measuring  Materials  and  Mixing  Concrete. 

14.  Measuring  Materials. — The  method  of  measuring  the  mater- 
ials for  the  concrete,  including  water,  shall  be  one  which  will  insure 
separate   and   uniform   proportions   of   each   of   the   materials   at    all 
times.     A  bag  of  Portland  cement   (94  Ibs.  net)   shall  be  considered 
one  ( 1 )  cu.  ft. 

15.  Mixing. — The    materials   shall    be   mixed    in    a   batch    mixer 
of  approved  type  and  mixing  shall  continue  after  all  materials  are 
in   the   drum   for  at  least  one    (1)    minute  at  a  minimum  speed  of 
twelve  (12)   revolutions  per  minute.     The  drum  shall  be  completely 
emptied  before  receiving  materials  for  successive  batches. 

16.  Re-Tempering. — Re-tempering  of  mortar  or  concrete  which 
has  partially  hardened,  that  is,  re-mixing  with  or  without  additional 
materials  or  water,  shall  not  be  permitted. 


6.  Placing   Concrete. 
Concrete  for  Base. 

17.  The   concrete  shall   be   mixed   with   the   proper   proportions, 
determined   as  herein   specified,   of  coarse   aggregate,   fine   aggregate, 
cement  and  water. 

18.  Immediately  prior  to  placing  the  concrete,  the  sub-grade  shall 
be  brought  to  an  even  surface.     The  surface  of  the  sub-grade  shall 
be  thoroly  wet,  but  shall  show  no  pools  of  water  when  the  concrete 
is  placed. 

After  mixing,  the  concrete  shall  be  deposited  rapidly  upon  the 
sub-grade  to  the  required  depth  and  for  the  entire  width  of  the 
pavement  in  successive  batches  and  in  a  continuous  operation  with- 
out the  use  of  intermediate  forms  or  bulkheads  between  expansion 
joints. 

The  concrete  shall  be  brought  to  an  even  surface,  the  thickness 
of  the  wearing  course,  below  the  established  grade  of  the  pavement. 
Workmen  shall  not  be  allowed  to  walk  on  the  freshly  laid  concrete, 
and  if  sand  or  dust  collects  on  the  base,  it  shall  be  removed  before 
the  wearing  course  is  applied.  The  reinforcing  metal  shall  be 
placed  upon  and  slightly  pressed  into  the  concrete  base  immediately 
after  it  is  placed. 

10 


In  case  of  a  breakdown,  concrete  shall  be  mixed  by  hand  to 
complete  the  section  or  an  intermediate  transverse  joint  placed  at 
the  point  of  stopping  work.  Any  concrete  in  excess  of  that  needed 
to  complete  a  section  at  the  stopping  of  work  shall  not  be  used  in 
the  work. 

7.    Concrete  for  the   Wearing   Course. 

19.  Mixture  No.  1. — The  concrete  for  the  wearing  course  shall 
be  mixed   in  the  manner  and  of  the  proportions    hereinbefore    de- 
scribed,   using   for    the   coarse    aggregate    No.    1    aggregate    for    the 
wearing  course  hereinbefore  specified. 

20.  Mixture  No.  2. — The  concrete  for  the  wearing  course  shall 
be  mixed  in  the  manner  and  of  the  proportions  hereinbefore  described, 
using   for   the   coarse   aggregate    No.    2    aggregate    for   the   wearing 
course,  herein  specified. 

21.  Placing. — The   wearing  course   shall   be  placed   immediately 
after  mixing,  and  in  no  case  shall  more  than  forty-five  (45)  minutes 
elapse  between  the  time  that  the  concrete  for  the  base  has  been  mixed 
and  the  time  the  wearing  course  is  placed. 

22.  Finishing. — The  wearing  course  shall  be  struck  off  for  the 
entire   wridth   of   the   pavement   and   from   back   to  back   of   integral 
curbs  when  used,  by  means  of  a  template  or  strike  board.     Any  holes 
left   by   removing  any   material   or   device   used   in   constructing   the 
joint  shall  be  immediately  filled  with  mortar  composed  of  one   ( 1 ) 
part  of  cement  and  two   (2)   parts  of  fine  aggregate.     Concrete  ad- 
joining metal  protection  plates  at  transverse  joints  shall  be  dense  in 
character,  and  shall  be  given  a  smooth  finish  with  a  steel  trowel  for 
a  distance  of  six  (6)  in.  on  each  side  of  the  joints. 

After  being  brought  to  the  established  grade  with  the  template 
or  strikeboard,  the  concrete  shall  be  finished  from  a  suitable  bridge, 
no  part  of  which  shall  come  in  contact  writh  the  concrete.  If  ap- 
proved by  the  engineer,  the  contractor  may  use  a  mechanical  strik- 
ing and  finishing  machine.  The  concrete  shall  be  finished  with  a 
wood  float  in  a  manner  to  thoroly  compact  it  and  produce  a 
surface  free  from  depressions  or  inequalities  of  any  kind.  The  fin- 
ished surface  of  the  pavement  shall  not  vary  more  than  one-quarter 
(T4")  in.  from  the  true  shape. 

11 


8.  Protection. 

23.  Curing  and   Protection. — Excepting  as   hereinafter  specified, 
the  surface  of  the  pavement  shall  be  sprayed  with  water  as  soon  as 
the  concrete  is  sufficiently  hardened  to  prevent  pitting,  and  shall  be 
kept  wet  until  an  earth  or  other  approved  covering  is  placed.     As 
soon  as  it  can  be  done  without  damaging  the  concrete,  the  surface 
of  the  pavement  shall  be  covered  with  not  less  than  two   (2)   in.  of 
earth  or  other  material  approved  by  the  engineer,  which  cover  shall 
"be  kept  wet  for  at  least  ten   (10)   days.     When  deemed  necessary  or 
advisable   by  the  engineer,    freshly   laid   concrete  shall   be  protected 
by  canvas  until  such  covering  can  be  placed. 

Under  the  most  favorable  conditions  for  hardening  in  hot  weather, 
the  pavement  shall  be  closed  to  traffic  for  at  least  fourteen  (14) 
days  and  in  cool  weather  for  an  additional  time,  to  be  determined 
by  the  engineer. 

At  the  season  of  the  year  when  the  average  temperature  is  below 
50  degrees  Fahrenheit,  sprinkling  and  covering  of  the  pavement  may 
be  omitted  at  the  direction  of  the  engineer. 

The  contractor  shall  erect  and  maintain  suitable  barriers  to  pro- 
tect concrete  from  traffic  and  any  part  of  the  pavement  damaged 
from  traffic  or  other  causes,  occuring  prior  to  its  official  acceptance, 
shall  be  repaired  or  replaced  by  the  contractor  at  his  expense,  in  a 
manner  satisfactory  to  the  engineer.  Before  the  pavement  is  thrown 
open  to  traffic  the  covering  shall  be  removed  and  disposed  of  as 
directed  by  the  engineer. 

24.  Temperature  Below  35  Degrees  Fahrenheit. — Concrete  shall 
not  be  mixed  or  deposited  when  the  temperature  is  below  freezing. 

If  at  any  time  during  the  progress  of  the  work  the  temperature 
is  or,  in  the  opinion  of  the  engineer  will  within  twenty-four  (24) 
hours  drop  to  thirty-five  (35)  degrees  Fahrenheit,  the  water  and 
aggregates  shall  be  heated,  and  precautions  taken  to  protect  the  work 
from  freezing  for  at  least  ten  (10)  days.  In  no  case  shall  concrete 
be  deposited  upon  a  frozen  sub-grade. 


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